phenethicillin

noun

phe·​neth·​i·​cil·​lin fi-ˌneth-ə-ˈsil-ən 

: a semisynthetic penicillin administered orally in the form of its potassium salt C₁₇H₁₉KN₂O₅S and used especially in the treatment of less severe infections caused by bacteria that do not produce beta-lactamase